Water levels at record lows in Upper Thames watershed

Thursday, May 3, 2012

by SUSAN MANN

Continuing dry conditions in a chunk of southern Ontario stretching from Stratford to London may impact water quality, aquatic animals and well levels, say officials with the Upper Thames River Conservation Authority.

“We have seen a general trend in our groundwater monitoring system of below normal water levels, not only in shallower wells but also in some deeper well,” authority hydrogeologist Linda Hicks says in a press release.

The Upper Thames Conservation area includes Stratford and Mitchell to the north, Woodstock to the east, Ingersoll, Tavistock and finally London on the southwestern edge. The authority covers the upper watershed of the Thames River an area of 3,482 square kilometres.

Senior water resources engineer Mark Shifflett says the authority’s Low Water Response Team moved its low water condition advisory to a Level 2 from the Level 1 declared in early April. That change indicates conditions are getting drier. The Levels 1, 2 and 3 are part of the three-tiered advisory system used to inform the public about low water conditions. A Level 3 would indicate conditions had gotten drier from the Level 2.

“The streams in this area are at record lows for April,” Shifflett says. Normally streams are at their lowest level at the end of the summer. But “what we’re seeing now is what we’d normally see in a dry year at the end of the summer.”

Shifflett called it an “extraordinarily dry period” for the Upper Thames area.

April was the Upper Thames watershed’s third straight month of below normal precipitation. The authority’s rain gauges measured only 25 per cent to 35 per cent of the rain normally received in April. Environment Canada’s London airport gauge recorded 25.6 millimetres of rain in April, the lowest total for that month in more than 60 years.

The area is below normal for rainfall by 120 millimetres so far this year. It will take several months of above normal rainfall before “we caught up,” he says.

Shifflett says there aren’t many farmers who irrigate fields directly from the Upper Thames watershed’s rivers or streams. The Ontario Environment Ministry regulates growers through their permit process. Many of the permits have restrictions on them when the streams are lower and Shifflett says with the dry conditions there could be a significant effect on anyone who is irrigating from a stream. BF